The present disclosure relates generally to heating, ventilation and air conditioning (HVAC) systems and, more particularly, to an integrated, high efficiency blower apparatus for HVAC systems.
A majority of residential (and many commercial) HVAC units employ forwardly curved (FC) centrifugal blowers in order to draw air into the HVAC units from the spaces to be heated or cooled, and to simultaneously push heated or cooled air from the units back into the spaces to be heated or cooled. The FC centrifugal blowers used in these types of HVAC units (i.e., where duty is comparatively light and it is desirable to keep the initial cost of the HVAC unit low) are advantageous from the standpoint of requiring a relatively smaller blower housing and typically operating at lower rotational speeds. However, the static efficiency of an FC blower is fairly low because of the inherent aerodynamic characteristics of FC blades. One way to improve upon the blower efficiency of an HVAC unit is to utilize an electronically commutated motor (ECM) in lieu of a more traditional single-speed induction motor, as is described more fully in U.S. Pat. No. 4,806,833 to Young.
On the other hand, backwardly curved (BC) or inclined blowers have higher static efficiency and total efficiency at higher operating speeds and pressures. However, the speed vs. torque curves of a BC blower are overlapped with one other, and thus cannot be used for the same flow control as FC blades. As such, it is challenging to combine both flow controllability and high efficiency performance in a HVAC blower system. In addition, residential HVAC systems have limited packaging space for blower assemblies. Thus, the overall efficiency of a BC blower in combination with an ECM may still be compromised by poor housing and fan design, notwithstanding the improvement in efficiency over a unit with a forwardly curved blower.
Accordingly, it is desirable to be able to reduce energy consumption of an HVAC system by improving airflow controllability, in view of the torque-speed characteristics of backwardly curved blowers.